package org.apache.solr.spelling;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.analysis.WhitespaceAnalyzer;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.core.SolrCore;
import org.apache.solr.schema.FieldType;
import org.apache.solr.search.SolrIndexSearcher;

import java.io.IOException;
import java.util.Collection;

/**
 * <p>
 * Refer to <a
 * href="http://wiki.apache.org/solr/SpellCheckComponent">SpellCheckComponent
 * </a> for more details.
 * </p>
 * 
 * @since solr 1.3
 */
public abstract class SolrSpellChecker {
	public static final String DICTIONARY_NAME = "name";
	public static final String DEFAULT_DICTIONARY_NAME = "default";
	public static final String FIELD = "field";
	public static final String FIELD_TYPE = "fieldType";
	/** Dictionary name */
	protected String name;
	protected Analyzer analyzer;
	protected String field;
	protected String fieldTypeName;

	public String init(NamedList config, SolrCore core) {
		name = (String) config.get(DICTIONARY_NAME);
		if (name == null) {
			name = DEFAULT_DICTIONARY_NAME;
		}
		field = (String) config.get(FIELD);
		if (field != null && core.getSchema().getFieldTypeNoEx(field) != null) {
			analyzer = core.getSchema().getFieldType(field).getQueryAnalyzer();
		}
		fieldTypeName = (String) config.get(FIELD_TYPE);
		if (core.getSchema().getFieldTypes().containsKey(fieldTypeName)) {
			FieldType fieldType = core.getSchema().getFieldTypes()
					.get(fieldTypeName);
			analyzer = fieldType.getQueryAnalyzer();
		}
		if (analyzer == null) {
			analyzer = new WhitespaceAnalyzer(
					core.getSolrConfig().luceneMatchVersion);
		}
		return name;
	}

	public Analyzer getQueryAnalyzer() {
		return analyzer;
	}

	public String getDictionaryName() {
		return name;
	}

	/**
	 * Reloads the index. Useful if an external process is responsible for
	 * building the spell checker.
	 * 
	 * @throws java.io.IOException
	 */
	public abstract void reload(SolrCore core, SolrIndexSearcher searcher)
			throws IOException;

	/**
	 * (re)Builds the spelling index. May be a NOOP if the implementation
	 * doesn't require building, or can't be rebuilt.
	 */
	public abstract void build(SolrCore core, SolrIndexSearcher searcher);

	/**
	 * Assumes count = 1, onlyMorePopular = false, extendedResults = false
	 * 
	 * @see #getSuggestions(Collection, org.apache.lucene.index.IndexReader,
	 *      int, boolean, boolean)
	 * 
	 * @deprecated This method will be removed in 4.x in favor of
	 *             {@link #getSuggestions(org.apache.solr.spelling.SpellingOptions)}
	 */
	@Deprecated
	public SpellingResult getSuggestions(Collection<Token> tokens,
			IndexReader reader) throws IOException {
		return getSuggestions(tokens, reader, 1, false, false);
	}

	/**
	 * Assumes onlyMorePopular = false, extendedResults = false
	 * 
	 * @see #getSuggestions(Collection, org.apache.lucene.index.IndexReader,
	 *      int, boolean, boolean)
	 * 
	 * @deprecated This method will be removed in 4.x in favor of
	 *             {@link #getSuggestions(org.apache.solr.spelling.SpellingOptions)}
	 */
	@Deprecated
	public SpellingResult getSuggestions(Collection<Token> tokens,
			IndexReader reader, int count) throws IOException {
		return getSuggestions(tokens, reader, count, false, false);
	}

	/**
	 * Assumes count = 1.
	 * 
	 * @see #getSuggestions(Collection, org.apache.lucene.index.IndexReader,
	 *      int, boolean, boolean)
	 * 
	 * @deprecated This method will be removed in 4.x in favor of
	 *             {@link #getSuggestions(org.apache.solr.spelling.SpellingOptions)}
	 */
	@Deprecated
	public SpellingResult getSuggestions(Collection<Token> tokens,
			IndexReader reader, boolean onlyMorePopular, boolean extendedResults)
			throws IOException {
		return getSuggestions(tokens, reader, 1, onlyMorePopular,
				extendedResults);
	}

	/**
	 * Get suggestions for the given query. Tokenizes the query using a field
	 * appropriate Analyzer. The {@link SpellingResult#getSuggestions()}
	 * suggestions must be ordered by best suggestion first.
	 * 
	 * @param tokens
	 *            The Tokens to be spell checked.
	 * @param reader
	 *            The (optional) IndexReader. If there is not IndexReader, than
	 *            extendedResults are not possible
	 * @param count
	 *            The maximum number of suggestions to return
	 * @param onlyMorePopular
	 *            TODO
	 * @param extendedResults
	 *            TODO
	 * @throws IOException
	 * 
	 * @deprecated This method will be removed in 4.x in favor of
	 *             {@link #getSuggestions(org.apache.solr.spelling.SpellingOptions)}
	 */
	@Deprecated
	public abstract SpellingResult getSuggestions(Collection<Token> tokens,
			IndexReader reader, int count, boolean onlyMorePopular,
			boolean extendedResults) throws IOException;

	/**
	 * Get suggestions for the given query. Tokenizes the query using a field
	 * appropriate Analyzer. The {@link SpellingResult#getSuggestions()}
	 * suggestions must be ordered by best suggestion first.
	 * <p/>
	 * Note: This method is abstract in Solr 4.0 and beyond and is the
	 * recommended way of implementing the spell checker. For now, it calls
	 * {@link #getSuggestions(java.util.Collection, org.apache.lucene.index.IndexReader, boolean, boolean)}.
	 * 
	 * 
	 * @param options
	 *            The {@link SpellingOptions} to use
	 * @return The {@link SpellingResult} suggestions
	 * @throws IOException
	 *             if there is an error producing suggestions
	 */
	public SpellingResult getSuggestions(SpellingOptions options)
			throws IOException {
		return getSuggestions(options.tokens, options.reader, options.count,
				options.onlyMorePopular, options.extendedResults);
	}

}
